This invention relates to melting furnaces and, more particularly, to a rotary scrap melting furnace that tilts and swivels.
Known processes are used to recover a metal, such as aluminum, from scrap containing that metal plus other substances. One such metal recovered is aluminum, which is used extensively in conjunction with iron, such as in engine blocks. It is usual to comminute the scrap and to heat it in a hearth furnace, which is heated to a temperature in range of 1400xc2x0 F. to 2000xc2x0 F. to melt the aluminum but not the iron or other substances.
At the end of the melting cycle, gates are opened to flow off the molten aluminum. The remaining scrap must then be manually removed or raked out of the melting chamber to prepare for another charge of scrap. The scrap removal operation is inefficient and overly long, which limits the cost effectiveness of the aluminum extraction process.
One advance in this process was the use of a rotary furnace in which a hollow drum is fitted for power rotation. Scrap is introduced through a front opening in the drum, which is then closed by a door. A rear burner is activated to melt the aluminum while the drum is rotated. The drum is also fitted for tilting about a transverse axis. It is tilted rearward to discharge the molten aluminum through a door, then is tilted forward to discharge the residual scrap materials. Such a rotary melting furnace is shown in U.S. Pat. No. 4,697,792xe2x80x94Fink. Such an arrangement is characterized by moving scrap wagons to and from the furnace, and moving receptacles for the molten aluminum to the furnace. The apparatus disclosed in this patent improves cycle time over the hearth melting method, but employs a cumbersome apparatus.
It would be desirable to provide a melting furnace and system that markedly improves cycle time.
It is therefore an object of this invention to provide a melting furnace and system that markedly improves cycle time.
The melting furnace and system of this invention is useful to rapidly process scrap that contains any of a plurality of metals which can be extracted from the scrap. Such metals include aluminum, zinc, lead, copper and brass. Any type of scrap can be processed without pre-processing comminution through a hammer mill or scrap chopper.
In one aspect, this invention features a rotary furnace for melting a metal containing scrap to separate and remove that metal from the residual scrap. The furnace comprises a hollow elongated drum having a circular body having a snout which tapers toward a reduced diameter front opening that is sized to receive and discharge uncomminuted metal-containing scrap. A door for closing the front opening is mounted for swinging movement to open and close the front opening. A power rotary drive rotates the drum about its longitudinal axis, while the drum is mounted on a base for tilting about a transverse axis by power tilters. The base is mounted for swiveling movement by a power swivel drive about a vertical axis to swivel the drum between a plurality of circumferentially-spaced operating stations. A heater is provided for heating the scrap in the drum.
In another aspect, the furnace of this invention features a drum which is charges with scrap through the opening, the molten metal is discharged through the opening and the residual scrap is discharged through the opening. Each of these operations occurs at discrete operating stations between which the drum is swiveled.
Preferably, the drum snout has a taper of about 15xc2x0, which enables a controlled discharge of the molten metal.
Another feature of this invention is that the drum is level when charged with scrap, is tilted backward about 20xc2x0 and rotated for melting, is tilted forward about 24xc2x0 and stopped to pour out the molten metal, and is tilted forward about 24xc2x0 and rotated to discharge the residual scrap.
In a further aspect, the drum interior is faceted to enhance tumbling of scrap during rotation, which aids in discharge of the residual scrap.
In a broader sense, this invention features the use of the swivel tiltable rotary drum furnace in a system that includes a scrap charging machine at a charging station for charging the furnace with scrap, a molten metal pouring station which can use a crucible, a holding/melting furnace or sows, and a discharging station for discharging the residual scrap. Also included is a furnace hood for collecting furnace air containing smoke and pollutants, a ventilation system for evacuating the furnace air, and a baghouse for removing pollutants and particulate matter from the evacuated air.
A yet further aspect of this invention features a method of recycling a metal by melting it to remove it from metal-containing scrap a tiltable, swivel rotary furnace. The method comprises the steps of providing such a furnace, swiveling the furnace to a first station for receiving metal-containing scrap, tilting back and rotating the furnace while heating to melt the metal, swiveling the furnace to a second station where the furnace is stopped and forward tilted to quickly pour off the molten metal into a holding apparatus, swiveling the furnace to a third station where the furnace is further forward tilted and rotated to discharge the residual scrap, and leveling and swiveling the furnace to the first station while still hot to receive metal-containing scrap, thereby reducing the amount of energy required to reheat the furnace to melting temperature.
These and other objects and features of this invention will become more readily apparent upon reference to the following detailed description of a preferred embodiment, as illustrated in the accompanying drawings, in which: